This invention claims the benefit of Japanese Patent Application No. 10-351622, filed on Dec. 10, 1998, which is hereby incorporated by reference.
1. Field of the Invention
The invention relates to configurations for a projection light used for illumination or signaling functions, and more particularly to configurations for vehicle lights such as a headlight, fog light, tail light, turn signal light, or traffic light for roadways and railroads. The projection light is generally circular in a front view and can include a light source, an ellipse group reflecting surface and a thick front lens. The projection light distribution is basically determined by the principles of the projection of a focused images. The projection light includes the following light ray path: light rays are emitted from the light source and reflected by the reflector, focused to at least one point, then projected to travel through the thick circular front lens. The ellipse group reflecting surface is defined by a reflecting surface that has a cross-section formed as an ellipse or similar shape such as a rotated parabolic surface, a complex elliptic surface, or an elliptical free-curved surface.
2. Discussion of the Related Art
FIGS. 15-17 illustrate configurations of conventional lights that can be used as a vehicle or traffic light. A conventional vehicle light 90 shown in FIG. 15 includes a light source 91, a rotated parabolic surface reflector 92 having a focus on the light source 91, and a front lens 93 having prismatic cuts 93a on its inner surface.
Light emitted from the light source 91 is reflected by the rotated parabolic surface reflector 92 to form parallel light rays. The reflected light is then diffused by the prismatic cuts 93a when passing through the front lens 93, thereby providing a predetermined light distribution.
FIG. 16 illustrates a horizontal cross sectional assembled view of another conventional vehicle light 80. The conventional vehicle light 80 includes a light source 81, a complex reflecting surface 82, and a front lens 83 that has no prismatic cuts. The complex reflecting surface 82 can be parabolic with a focus located at the light source 81 in a vertical cross sectional assembled view, and configured as a complex paraboloidal solid surface composed of connected straight lines in a horizontal cross sectional assembled view. Light distribution patterns for the light 80 are formed by adjusting the complex reflecting surface 82.
FIG. 17 illustrates a conventional projection-type vehicle light 70 including a light source 71, an aspherical lens 73, an elliptical reflecting surface 72 having a first focus on the light source 71 and a second focus at which light reflected from the elliptical reflecting surface 72 converges. The focused image of light rays is enlarged and projected to the aspherical lens 73. The light rays are refracted by the aspherical lens 73 to create specific light distribution patterns for the projection-type vehicle light 70.
A shade 74 may be used to prohibit unnecessary light rays, e.g., high beam type light rays, from passing through the aspherical lens 73. The shade 74 includes a top portion located around the second focus of the elliptical reflecting surface 72.
Improvements to multi projection lens type projection lights are also disclosed in Japanese Patent Publication No. HEI 03-64962.
The conventional vehicle and traffic lights described above have the following problems. The vehicle light 90 in FIG. 15 does not have a substantially transparent front lens 93 and therefore cannot provide a three dimensional feeling. These features are becoming important requirements in the market. The prismatic cuts 93a must have optical function, requiring deep straight line cuts or curved line cuts having great curvature. Accordingly, the lens 93 is relatively thick, and the transparency of the lens 93 is deteriorated.
The vehicle light 80 in FIG. 16 has superior transparency because the lens 83 does not have any prismatic cuts. However, it is difficult to adjust the complex reflecting surface 82 and therefore is also difficult to obtain a sufficiently wide light distribution pattern. The light distribution patterns of the vehicle light 80 are determined by adjusting the entire combined complex reflecting surface 82. Adjustment cannot be easily achieved by manipulation of discrete portions of the complex reflecting surface 82.
The projecting-type vehicle light 70 in FIG. 17 is very long and deep and is difficult to design and/or place into a vehicle body. In addition, the external diameter of the aspherical lens 73 is small, and thus the light emitting area of the projection-type vehicle light 70 is small. When the projection-type vehicle light 70 is used as a headlight, visibility of a vehicle incorporating the projection-type vehicle light 70 is reduced as viewed from another vehicle traveling in an oncoming lane.
The vehicle lights 70, 80, 90 are commonly used in the market but lack design uniqueness and do not provide a novel appearance. Furthermore, none of the vehicle lights 70, 80, 90 provides sufficient efficiency when the depth of the light is reduced because efficiency of lumen output of a light source depends on the depth of the vehicle light.
The vehicle lamp disclosed in Japanese Patent Publication No. HEI 03-64962 has the following problems. Since optical axes of the respective aspherical lenses are aligned in different directions from each other, light distribution patterns of the vehicle lamp are formed by a combination of the light distributions from the aspherical lenses. Therefore, there is a tendency for the connecting lines of respective light distribution patterns for each aspherical lens to clearly appear in the light distribution pattern of the vehicle lamp. The light distribution patterns of this projection-type vehicle light is often thought of as not thoroughly uniform. Furthermore, utilization efficiency of reflected light by the elliptical reflecting surface is small. The second focus of the elliptical reflecting surface and the focus of aspherical lens is a common point. The radius of curvature of the aspherical lens is not the same as the radius of curvature of the ellipse. The aspherical lens is not located in a position in which the imaginary hemispherical portion which is a mirror of the elliptical reflecting surface is located. Therefore, a considerable amount of the light rays that are reflected by the elliptical reflecting surface are not incident to the aspherical lens, especially light rays that are reflected by the substantially lower half portion of the elliptical reflecting surface. Although the elliptical reflecting surface extends towards the aspherical lens without changing the diameter of the aspherical lens 4, the amount of light incident on the aspherical lens 73 does not substantially improve. Light rays reflected by the extended reflecting portion are not incident to the aspherical lens 73 because the focus of the aspherical lens 73 is a point. Additionally, light rays reflected by the lower half portion of the reflector from the light source are not incident to the aspherical lens 73 if the optical axes of the reflector and the aspherical lens are parallel to each other, because the light rays reflected by the lower half portion become upwardly directed light rays which are not necessary for the formation of the passing-by low beam light distribution pattern. To obtain a larger amount of light, the overall size of the projection-type vehicle light must be enlarged.
The invention is directed to a projection-type vehicle headlight or traffic light that substantially obviates one or more of the above problems due to the limitations and disadvantages of the related art.
An object of the invention is to provide a projection-type vehicle light that has a novel appearance with superior transparency of he front lens and which provides a three dimensional aspect to a viewer.
Another object of the invention is to provide a projection-type vehicle light that has sufficient light emitting area and is capable of providing wide and highly uniform light distribution patterns, especially in the horizontal plane.
Still another object of the invention is to provide a projection light with high incident efficiency of light rays reflected by a reflecting surface to an aspherical lens.
The above objects can be achieved by providing a projection-type vehicle light including a light source positioned in a reflector, a front lens including a plurality of aspherical lenses and a reflector including at least one reflector unit or combination thereof for directing reflected light rays such that they are incident to a corresponding aspherical lens. The reflector unit can include the following:
1. A plurality of ellipse group reflector units having a common first focus around the light source and a plurality of second foci respectively positioned between a focus of a corresponding aspherical lens and a front end of the corresponding aspherical lens;
2. A plurality of ellipse group reflector units having a common first focus on the light source, and a second focus which is a curved line intersecting a respective focus of a corresponding aspherical lenses;
3. An ellipse group reflector unit including an upper reflecting surface and a lower reflecting surface divided along a horizontal central line of a corresponding aspherical lens, and wherein the upper reflecting surface has a first focus at a front end of the light source and the lower reflecting surface has a first focus at a back end of the light source; and
4. An ellipse group reflector unit including a plurality of reflecting surface segments divided from a vertical central line of a corresponding aspherical lens toward both right and left ends in predetermined intervals, wherein each reflecting surface segment has a common first focus around the light source, and wherein second foci of reflecting surface segments form a curved line connecting respective foci of the corresponding aspherical lenses in a horizontal cross sectional view, and each second focus is positioned above the horizontal center line of the corresponding aspherical lens in a vertical cross sectional view.
In accordance with an aspect of the invention, the light can include a light source, a lens located adjacent the light source and including a plurality of aspherical lenses each having an aspherical focus, and a reflector located adjacent the light source, wherein the reflector includes a plurality of ellipse group reflector units having a common first focus located substantially at the light source and each reflector unit having a second focus respectively located substantially between an aspherical focus of a corresponding aspherical lens and a front portion of the aspherical lens.
In accordance with another aspect of the invention, the light can include a light source, a lens including a plurality of aspherical lenses each having an aspherical focus, and a reflector including a plurality of ellipse group reflector units having a common first focus located substantially at the light source and each reflector unit having a second focus forming a curved line and located substantially at a respective aspherical focus of a corresponding aspherical lens.
In accordance with another aspect of the invention, the light can include a light source, a lens including a plurality of aspherical lenses each having an aspherical focus, and a reflector including an ellipse group reflector unit that has an upper reflecting surface and a lower reflecting surface divided along a horizontal central line, wherein the upper reflecting surface has an upper focus and the lower reflecting surface has a lower focus positioned at a different location from the upper focus.
In accordance with another aspect of the invention, the light can include a light source, a lens including a plurality of aspherical lenses each having an aspherical focus, and a reflector including an ellipse group reflector unit having a plurality of reflecting surface segments, the reflecting surface segments having a common first focus located substantially at the light source and each of the reflecting surface segments having a second focus forming a curved line and located substantially at a respective aspherical focus of a corresponding aspherical lens as viewed in a horizontal cross sectional view, and each second focus being positioned above a horizontal center line of a corresponding aspherical lens as viewed in a vertical cross sectional view.
In accordance with another aspect of the invention, the light can include a light source, a lens including a plurality of aspherical lenses each having an aspherical focus, and a reflector having an upper half portion and a lower half portion, the upper half portion including a rotated elliptical surface with a first upper focus located substantially at the light source and a second upper focus located substantially at an aspherical focus of a corresponding aspherical lens, the lower half portion having a rotated parabolic surface with a first lower focus located substantially at said light source.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.